Electron microscopic and autoradiographic studies of precancerous and cancerous lesions of the large intestine will be continued in order to describe the epithelial-mesenchymal relationships in this tissue in comparison to that in the normal and hyperplastic colonic mucosa. In addition, the fine structure of the cells of the adenocarcinomas and carcinoids of the colon will be critically analyzed for differences from that of the precancerous adenomatous lesions. Investigations on mesenchymal cell renewal in adult tissues will continue to focus on the relation between this phenomenon and the development of unusual soft tissue tumors. Both clinicopathologic studies of surgical diagnostic material and experimental autoradiographic studies of the same tissues in rabbits will continue. Correlated studies of corneal cell morphology and physiologic and biochemical function will continue with emphasis on the development and further use of the corneal endothelial culture system as a model system for studying synthesis of extracellular materials and for studying the transport of materials across the endothelium. In addition, studies will continue on the efficacy of various storage procedures for the maintenance of corneal viability.